Why wireless links provide lower reliability compared to wired links? You turn o
ID: 3696743 • Letter: W
Question
Why wireless links provide lower reliability compared to wired links? You turn on your phone and after few seconds you can see a list of available 802.11 networks. From the 802.11 protocol point of view, how does this happens? Ethernet and 802.11 are both data-link layer protocols designed for wired and wireless networks, respectively. Why a 802.11 receiver expects ACK reception while Ethernet does not have such requirement. Where CSMA/CD and CSMA/CA are used? and what are the differences? What are the main differences between 2G, 3G, and LTE cellular networks? explain your answer in terms of architecture and the communication speed provided.Explanation / Answer
1.Why wireless links provide lower reliability compared to wired links?
Answer:
Wireless links provide lower reliability compared to wired links due to its high bit error rate caused by handoffs.
2.You turn on your phone and after few seconds you can see a list of available 802.11 networks.From 802.11 protocol point of view,How does this happens?
Answer:
Wireless Auto Configuration minimizes the configuration that is required to access wireless networks and you to travel to different wireless networks without reconfiguring the network connection settings on your computer for each location. For the initial scan of available wireless networks, Wireless Auto Configuration performs the following process.i.e.
(i) Wireless Auto Configuration attempts to connect to the preferred networks that appear in the list of available networks in the preferred networks preference order.
(ii) If th ere are no successful connections, it attempts to connect to the preferred networks that do
not appear in the list of available networks.
(iii) If there are no successful connections and there is an ad hoc network in the list of preferred networks that is
available.Wireless Auto Configuration tries to connect to it.
(iv)If there are no successful connections, and there is an ad hoc network in the list of preferred networks that is not available, Wireless Auto Configuration configures the wireless network adapter to act as the first node in the ad hoc network.
(v) If there are no successful connections to preferred networks, and there are no ad hoc networks in the list of preferred networks, Wireless Auto Configuration determines the Automatically Connect To Non-Preferred Networks setting
(vi) If the Automatically Connect To Non-Preferred Networks setting is disabled, Wireless Auto Configuration creates a random network name and places the wireless network adapter in infrastructure mode.
vii)If the Automatically Connect To Non-Preferred Networks setting is enabled, Wireless Auto Configuration attempts to connect to the available networks in the order in which the wireless adapter sensed them.
3.Ethernet and 802.11 protocols are both data link layer protocolsdesigned for both wired and wireless networks.Why a 802.11 receiver expect ACK receiption while ethernet does not have such requirement?
Answer:
In an 802.11 WLAN, one computer does not send a packet exclusively to another computer. Instead, it puts the address of the desired destination or receiving station in the header of the packet, and puts the packet out onto the airwaves. Each network node within range listens to the transmission and uses the first address in the 802.11 WLAN MAC header to determine if that node should process it. If the packet was intended for a particular computer, that machine captures it, puts it in memory, and then passes it to the next layer of the protocol stack for processing. If the message was received intact, the receiving node typically sends an ACK to acknowledge this. But in ethernet a packet is sent exclusively to another computer.Here the communication process is predetermined.Therefore in ethernet ACK is not expected.
4.Where CSMA/CD and CSMA/CA are used and what are the differences?
Answer:
Carrier sense multiple access with collision avoidance (CSMA/CA)is a network multiple access method in which carrier sensing is used, but nodes attempt to avoid collisions by transmitting only when the channel is sensed to be idle.When they do transmit, nodes transmit their packet data in its entirety.It is particularly used in wireless networks e.g IEEE.802.11 Wireless LAN.CSMA/CA protocol operates in the Data Link Layer of the OSI model.Carrier sense multiple access with collision detection (CSMA/CD) is a media access control method used most notably in local area networking using early Ethernet technology. It uses a carrier sensing scheme in which a transmitting data station detects other signals while transmitting a frame, and stops transmitting that frame, transmits a jam signal, and then waits for a random time interval before trying to resend the frame.It is particularly used in wired networks e.g.ethernet.
5.What are the main difference between 2G,3G and LTE cellular networks?Explain your answer in terms of architecture and the communication speed provided.
Answer:
The speed of data transmission in 2G network is less than 50,000 bits per sec while in 3G it can be more than 4 million bits per sec.The main function of 2G technology is the transmission of information via voice signals while that of 3G technologies is data transfer via video conferencing, MMS etc.The features like mobile TV, video transfers and GPS systems are the additional features of 3G technology that are not available with 2G technologies. 2G technology uses a broad range of frequencies in both upper and lower bands, under which the transmission depends on conditions such as weather. A drawback of 3G is that it is simply not available in certain regions.The downloading and uploading speeds available in 2G technologies are up to 236 Kbps. While in 3G technology the downloading and uploading speeds are up to 21 Mbps and 5.7 Mbps respectively.LTE (LongTerm Evolution) is a standard for wireless communication of high-speed data formobile phones and data terminals. Peak download rates up to 299.6 Mbit/s and upload rates up to 75.4 Mbit/s depending on the user equipment category. Five different terminal classes have been defined from a voice centric class up to a high end terminal that supports the peak data rates. All terminals will be able to process 20 MHz bandwidth.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.